Massachusetts Sen. Elizabeth Warren formally backed former Vice President Joe Biden for president on Wednesday, over a month after she ended her own campaign, rounding out a string of big endorsements as party leaders rally around the presumptive Democratic nominee. "In this moment of crisis, it's more important than ever that the next president restores Americans' faith in good, effective government—and I've seen Joe Biden help our nation rebuild," Warren said in a tweet. Warren also put out a video explaining why she supports Biden, citing his life story and experience in public office. Biden and Warren also have a history of disagreement over a 2005 bankruptcy bill — legislation that tightened the requirements to file for bankruptcy. Biden supported the legislation as a senator from Delaware, home to a number of credit card companies, and Warren, then a professor at Harvard Law School, opposed it. They famously clashed in a Senate Judiciary Committee hearing on the bill. This long